Drain clams, reserving liquid.
Cook onion, parsley, and garlic in oil till onion is tender.
Stir in tomato sauce, tomato paste, reserved clam liquid, basil, sugar, pepper, and 1 1/2 cups water.
Cover and simmer 1 hour.
Add clams; heat through.
Cook linguini according to package directions; drain.
Pour sauce over linguini; serve with Parmesan.